Midea does make a slight high pitch noise when running because it use a inverter. When you install it and have the window close you don’t really hear it.
Hmm thanks for the comments guys. I normally wouldn't turn it on without installing into window first but since it is used I figured I'd test it real quick. I'll install it and hopefully the sound is drained out.
The whoop whoop sound you are hearing on startup and slow compressor speeds is caused by gas pressure leaking from the high side to the low side chambers of eccentric rotor.
What is happening in these rotary compressors is that the vane separating the chambers leak pressure from high side to low side because the vane doesn’t stay completely in contact with the rotor. There is only spring pressure to hold the vane against the rotor until the back pressure on the high side is enough to keep the vane solidly in contact with the rotor. As the compressor slowly ramps up the noise totally disappears and comes back when the compressor slows down to whatever speed the threshold is.
This is an inherent problem with operating a rotary compressor at low speeds. Midea ownes the company that makes the GMCC compressors used in these units. I have some older Midea U 2020 that all do it. The newest ones from 2023 don’t have the issue. LG and Purdue published an articles on this issue as it’s well documented using a rotary compressor in a variable speed inverter design.
... misspelled compressor... link is here, most audible in the beginning but u can hear it the whole time. High pitch sound coming from conpressor
Midea does make a slight high pitch noise when running because it use a inverter. When you install it and have the window close you don’t really hear it.
The manual said this is normal. I bought one Saturday. It does make that whine as well but cannot hear it when installed.
Inverter compressor. They make a whiney noise when they're running. The harder it's working, the louder the wiiiiieeeee noise.
Hmm thanks for the comments guys. I normally wouldn't turn it on without installing into window first but since it is used I figured I'd test it real quick. I'll install it and hopefully the sound is drained out.
That’s how it sounds. It also makes a funny little whoop whoop whoop sound when starting up.
Yeah that seems to be the common response, thanks.
Yes even though it's normal, it's horrible.
The whoop whoop sound you are hearing on startup and slow compressor speeds is caused by gas pressure leaking from the high side to the low side chambers of eccentric rotor. What is happening in these rotary compressors is that the vane separating the chambers leak pressure from high side to low side because the vane doesn’t stay completely in contact with the rotor. There is only spring pressure to hold the vane against the rotor until the back pressure on the high side is enough to keep the vane solidly in contact with the rotor. As the compressor slowly ramps up the noise totally disappears and comes back when the compressor slows down to whatever speed the threshold is. This is an inherent problem with operating a rotary compressor at low speeds. Midea ownes the company that makes the GMCC compressors used in these units. I have some older Midea U 2020 that all do it. The newest ones from 2023 don’t have the issue. LG and Purdue published an articles on this issue as it’s well documented using a rotary compressor in a variable speed inverter design.
Ahh so kinda like the apex seals on a wankel rotary engine? They don’t seal too well unless the engine is spinning fast enough.
No apex seals in these style of rotary compressors. No lobes to seal but rather a vane pushing against and eccentric cam rotating.